diff --git a/app/scodoc/sco_utils.py b/app/scodoc/sco_utils.py
index c2f6f2dde..20c351dae 100644
--- a/app/scodoc/sco_utils.py
+++ b/app/scodoc/sco_utils.py
@@ -152,7 +152,40 @@ def convert_fr_date(
     raise ScoValueError("Date (j/m/a) invalide")
 
 
-def heure_to_iso8601(t: str | datetime.time = None) -> str:
+# Various implementations of heure_to_iso8601 with timing:
+# def heure_to_iso8601_v0(t: str | datetime.time = None) -> str:  # 682 nsec per loop
+#     """Convert time string or time object to ISO 8601 (allows 16:03, 16h03, 16),
+#     returns hh:mm:ss or empty string
+#     """
+#     if isinstance(t, datetime.time):
+#         return t.isoformat()
+#     if not t:
+#         return ""
+#     parts = t.strip().upper().replace("H", ":").split(":")
+#     # here we can have hh, hh:mm or hh:mm:ss
+#     h = int(parts[0])
+#     m = int(parts[1]) if len(parts) > 1 and parts[1].strip() else 0
+#     s = int(parts[2]) if len(parts) > 2 and parts[1].strip() else 0
+#     return datetime.time(h, m, s).isoformat()
+
+
+# def heure_to_iso8601_v1(t: str | datetime.time = None) -> str:  # 581 nsec per loop
+#     """Convert time string or time object to ISO 8601 (allows 16:03, 16h03, 16),
+#     returns hh:mm:ss or empty string
+#     """
+#     if isinstance(t, datetime.time):
+#         return t.isoformat()
+#     if not t:
+#         return ""
+#     parts = t.strip().upper().replace("H", ":").split(":")
+#     # here we can have hh, hh:mm or hh:mm:ss
+#     h = int(parts[0])
+#     m = int(parts[1]) if len(parts) > 1 and parts[1].strip() else 0
+#     s = int(parts[2]) if len(parts) > 2 and parts[1].strip() else 0
+#     return "%02d:%02d:%02d" % (h, m, s)
+
+
+def heure_to_iso8601(t: str | datetime.time = None) -> str:  # 500 nsec per loop
     """Convert time string or time object to ISO 8601 (allows 16:03, 16h03, 16),
     returns hh:mm:ss or empty string
     """
@@ -163,9 +196,15 @@ def heure_to_iso8601(t: str | datetime.time = None) -> str:
     parts = t.strip().upper().replace("H", ":").split(":")
     # here we can have hh, hh:mm or hh:mm:ss
     h = int(parts[0])
-    m = int(parts[1]) if len(parts) > 1 else 0
-    s = int(parts[2]) if len(parts) > 2 else 0
-    return datetime.time(h, m, s).isoformat()
+    try:
+        m = int(parts[1])
+    except:
+        m = 0
+    try:
+        s = int(parts[2])
+    except:
+        s = 0
+    return "%02d:%02d:%02d" % (h, m, s)
 
 
 def print_progress_bar(
diff --git a/tests/unit/test_sco_utils.py b/tests/unit/test_sco_utils.py
index 4f0baa16d..afcd365bf 100644
--- a/tests/unit/test_sco_utils.py
+++ b/tests/unit/test_sco_utils.py
@@ -16,6 +16,7 @@ from app.scodoc.sco_exceptions import ScoValueError
 from app.scodoc.sco_utils import convert_fr_date, heure_to_iso8601
 
 
+# Dates humaines -> ISO
 def test_convert_fr_date_full_date():
     assert convert_fr_date("12/2/1972") == datetime.datetime(1972, 2, 12)
 
@@ -47,6 +48,9 @@ def test_convert_fr_date_invalid_iso_format():
         convert_fr_date("2022-02-30T00:00:00")
 
 
+# ---- Heures humaines -> ISO8601
+
+
 def test_heure_to_iso8601_full_time():
     assert heure_to_iso8601("16:01:02") == "16:01:02"
 
@@ -59,6 +63,10 @@ def test_heure_to_iso8601_hour_only():
     assert heure_to_iso8601("16") == "16:00:00"
 
 
+def test_heure_to_iso8601_hour_h():
+    assert heure_to_iso8601("16h") == "16:00:00"
+
+
 def test_heure_to_iso8601_single_digit():
     assert heure_to_iso8601("1:2:3") == "01:02:03"